Thank you for your question.
Unfortunately, export control is outside my remit, and I believe that on JA there are no European experts in the field.
However, I wanted to give you two starting points, where you can find official information, which is essential in this field. My recommendation (and theirs as well) is to write specifically to both offices (US and Germany) explaining the kind of service you intend to offer, and obtain a written reply that it does not fall into the restriction list.
The US-China export control regime is presented here: https://www.export.gov/article?id=China-U-S-Export-Controls
You will see that dealing with it requires specialist knowledge. Perhaps in the US section there are experts for this.
The German authority for export control is here: http://www.bafa.de/EN/Foreign_Trade/Export_Control/export_control_node.html
While they do not have one China-specific material, they have one good presentation material, here: http://www.bafa.de/SharedDocs/Downloads/EN/Foreign_Trade/afk_export_control_brief_outline.pdf?__blob=publicationFile&v=2
This being the best I can offer, please feel free not to rate if it does not meet your expectations (rather than giving a small rating). The money will revert to you with no charge, in this case. I hope I did help at least somewhat, though.
Dr I L Vlad